Watching a crane operator elevate and transport a heavy load over a significant distance to a precise location with an articulated crane is always a fascinating and thought-provoking activity. With today’s concerns about job safety, how is safety handled in this process? Safety begins with the skill of the crane operator but today’s sensors and advanced electronics enhance safety and provide warnings for potential problems.
Among the sensor involved in safely elevating and transporting the load are: tensiometers, length and angle sensors (boom position and jack angle), force transducers (load cells), outrigger load sensing, wheel speed sensors, incremental encoders and hydraulic pressure sensors. With safety criteria stored in the crane’s control system, the networked data from the various sensors are used to compute safe operating zones to avoid a maximum load from exceeding a critical angle and distance.
Other factors, including the need to complete the job within a narrow time window, can cause excessive and unsafe swaying of the suspended load. A closed-loop anti-sway controller consisting of a network of embedded microelectromechanical systems (MEMS) sensors for the crane’s motion state is among the proposals to make the crane’s operation even safer under increased time pressures. Sensing in this system involves global positioning system (GPS) sensing and accelerometers for feedback control.
Sensing abnormal hydraulic oil temperature, machine vibration or hydraulic pressure variations can alert the crane operator or even a remote monitoring station that the crane is either due for scheduled maintenance or detect a potential problem before it becomes a safety issue or causes unnecessary and unscheduled downtime.